Electricity may be employed to provide stimulation to the skin tissue or to facilitate drug transport across the skin barrier. In electricity-assisted devices, an electric potential (voltage) is applied to the skin membrane, to facilitate electricity passage, or ionic drug transport through the skin, the latter is called transdermal iontophoretic drug delivery. In transdermal iontophoresis, an ionized drug migrates into the skin driven by an applied electric potential gradient. Anionic drugs are delivered into the skin under the cathode (negatively charged electrode), while cationic drugs are delivered under the anode (positively charged electrode). Iontophoresis enables enhanced as well as better control of permeation rate of the ionic species into the skin.
The most common design of an iontophoresis device includes a power source (e.g., a battery), an electric control mechanism, and two separate conductive electrodes. Each conductive electrode is in contact with a separate electrolyte composition (with or without an active agent). The electrolyte or ionic active composition is generally either an aqueous solution contained in a liquid chamber or a semi-solid. The assembly of the conductive electrode and electrolyte composition is often referred to as “an electrode assembly” or simply “an electrode.” The two electrode assemblies are usually affixed to the skin separated by electric insulation between them.
Alternatively, the two electrode assemblies may be constructed into a single iontophoresis device with an electric insulating material built between the two electrode assemblies for electrical isolation to prevent shorting current. An example of such an iontophoresis device is disclosed in U.S. Pat. No. 5,387,189.
In another variation of the common iontophoresis device designs, the electrolyte composition in one of the two electrode assemblies is eliminated, and the conductive electrode is placed directly in contact with the skin to complete the electric circuit. An example of such iontophoresis device is disclosed in U.S. Pat. No. 6,385,487.
During a typical iontophoresis operation (mono-polar operation), one of the two electrodes (i.e., active electrode) drives the active agent into the skin. The other electrode (i.e., disperse electrode) serves to close the electrical circuit through the skin. Sometimes, a second active agent of opposite electric charge can be placed into electrolyte composition in contact with the second electrode, thus, being delivered into the skin under the second electrode. Alternatively, the electric polarity of the first and second electrodes can be reversed periodically to drive ionic species under both electrodes (bi-polar operation). A bi-polar iontophoresis device for transdermal drug delivery is disclosed U.S. Pat. No. 4,406,658.
Iontophoretic devices are also used for the treatment of hyperhydrosis, excessive sweating typically of the palms of the hands, the soles of the feet, or the axilla. It is estimated that approximately two percent of the population suffers from hyperhydrosis. Excessive sweating can lead to further dermatological disorders and social stigma. Besides iontophoresis, conventional treatments for hyperhydrosis include the use of antiperspirants, aluminum chloride, botulinum toxin injections, and surgical procedures such as extrathoracic sympathectomy. Iontophoretic devices for the treatment of hyperhydrosis are described in example U.S. Patent Appln. Publication No. 2004/0167461 to Nitzan et al. and U.S. Pat. No. 6,223,076 to Tapper. Nitzan et al. describe the use of a dermal patch that may be in the form of an article of clothing. The patch comprises an electrochemical cell having at least two electrodes positioned on one side of the dermal patch, the electrodes forming electrical contact with a skin portion of a subject. The patch is designed and configured for delivering an electric current through the skin and conductive fluid used in conjunction with the patch.
Tapper describes the delivery of an active ingredient, such as an antiperspirant, to a region of the human body using a device comprising a DC power source, a controller and a pair of electrodes. The electrodes are mounted in generally close proximity to one another and are separated by an insulating member. The device also comprises a pair of pads, each of which is positioned in adjacent contact with one of the electrodes. The electrodes are sized and arranged so that the tissue to be treated can extend across the insulating member and simultaneously contact both pads. The entire device, for example, fits within the armpit area. See also the Drionic Device, commercially available from General Medical Company (Los Angeles, Calif.), and the MD-1a Iontophoresis Unit commercially available from R.A. Fischer Company (North Ridge, Calif.).
Conventional iontophoretic devices like the above are less than optimal. They are inconvenient to use, and immobilize the patient during treatment. They also require the use of relatively high electric currents, around 18 milliamps, that are only manually adjustable, and which may, depending on the design, be directed through major portions of the body remote from the treatment area. They are also typically painful for the person undergoing treatment due to the high current. This is a particular problem in that treatment often requires several sessions over a period of weeks or months.
Devices and methods for the treatment of hyperhydrosis have now been discovered that are simple to use, allow patient movement, and are relatively pain free. They employ a user-friendly garment, such as a glove or sock, containing a first electrode for contacting the treatment area. A second electrode is positioned on the skin nearby inside or outside the treatment area. The location of the second electrode is adjustable according to the desire and comfort of the user. A power source connects the two electrodes and provides a low, adjustable electric current to the device. Importantly, the power source provides an electric current that is customizable for the patient, for example in current intensity and treatment duration. Optionally, a carrier such as water may be used to provide ionic communication between the first electrode, the second electrode, or both, and the skin.